Can't send control keys in web rdp session

Hello everyone

we have a ssl-vpn connection with enabled web mode, that we use to connect to a windows jump server with rdp. On the jump server we use putty to connect to different devices. With some text editors (e.g. nano) we have to send control keys after editing a file. Copying and pasting is not a problem, as I can use the remote desktop tools to accomplish this, but I can't send other control keys (e.g. ctrl+x), that are indispensable. There are ways I could circumvent this issue, but I would prefer to be able to use the control keys.

Is there a way to send control keys to the machine in web mode with a rdp connection?